Flystrike treatment & prevention

Blowflies are one of the most widespread ectoparasites affecting sheep in the UK, with surveys suggesting 80% of flocks will have one or more cases of blowfly strike every year. It seems that the current weather and climatic conditions are particularly favouring flystrike at the moment with our vets seeing quite a few cases so extra vigilance will be needed. We thought we would take the time to help remind you of the signs of strike and how to prevent this possibly fatal disease.

In the UK, blowfly strike is mainly caused by maggots of greenbottle, blackbottles and bluebottle flies, who are attracted to long fleece, wounds, footrot, soiled fleece or dead animals. Each female lays up to 250 eggs on the surface of the skin and in the fleece, they hatch after about 12 hours and when large numbers of maggots are present they start attacking the flesh itself.

Image courtesy of Dr Philip Scott and NADIS

What to look for

Signs of irritation leading to inappetance, dullness and depression

Foul smelling areas of moist, stained wool – dark green in colour. Especially around the back end, chest and feet

Kicking of the hind limbs and tail shaking

Maggots present at skin level upon parting the fleece

Skin lesions (from reddened areas to deeper wounds)

Image courtesy of Dr Philip Scott and NADIS

How to treat

Remove dirty, contaminated fleece as soon as possible around the whole area of the strike – it may be larger than it looked to begin with!

Wash the skin of as many maggots as possible and clean open wounds with salt water or skin disinfectant such as Hibiscrub or iodine

Apply topical antibiotic spray to affected areas of skin

Use a fly strike treatment preparation (e.g. deltamethrin or cypermethrin as an active ingredient) as instructed on the label around the area of flystrike e.g. Crovect, Dectospot, Spotinor or Deltanil. NB – CLiK products do not treat established strike

If the skin had been broken or the animal is very uncomfortable consider systemic antibiotics and anti-inflammatories

Keep a close eye on flystrike cases for the next few days and if you are worried contact your vet

How to prevent cases

Examine flock regularly during at risk periods – twice a day recommended for signs of strike or increased fly presence